They were convinced they had it coming because they had done something to anger their gods. Just like the liberals of today are convinced we did something wrong to bring about 9-11. The proposed solutions are not dissimilar. The Incas sacraficed their own people to these false gods. The liberals propose to sacrafice western civilization to appease the false gods of radical Islam.
It seems to work out better for a civilization if they believe in the Loving God scenario instead of the Angry God scenario.